Modern vehicles such as aircraft use a large number of electronics, motors, heaters, and other electrically-driven equipment. Electric motors, in particular, are ubiquitous in modern vehicles and drive everything from hydraulic pumps to cabin fans. Conventionally, each of these electric motors is driven by an independent motor controller. Each motor controller is sized to be able to carry the maximum amount of current required to power its respective motor at full power for an extended period of time (and generally, further includes some additional capacity for safety) without overheating or malfunctioning.
As a result, an aircraft carries a number of motor controllers, each of which is typically oversized and underutilized a majority of the time. In other words, the motor controller includes enough capacity to run the motor at full power for an extended period of time plus a safety margin, but motors are rarely, if ever, run at full capacity. This is because the motors themselves have some safety margin built in and because, a majority of the time, the motors are operating in a lower demand regime (e.g., the cabin fan is not always on “High”). In addition, some motors are only used occasionally, or during specific flight segments, and are unused the remainder of the time. As a result, many of an aircraft's complement of heavy, expensive motor controllers spend a majority of their service life either inactive or operating significantly below their rated power outputs.
To better utilize motor controller capacity, a modular converter system can provide multiple, modular, assignable, dynamically reconfigurable motor controllers that can work alone or in parallel with other parallel motor controllers to meet power control needs. The converter system connects one or more controllers, connected in parallel, to each active electrical load in the aircraft, as necessary, to meet existing power demands. Increasing utilization of motor controllers can provide a corresponding reduction in system weight and cost.
During operation of the modular converter system, a plurality of inverters can be operated in parallel to power an electric motor or another electrical load. Conventionally, the number of parallel inverters used to drive a particular electrical load is based solely on the power demand of the electrical load and the rated power of the inverters, but does not consider the efficiency of each inverter within such a parallel arrangement. For example, based on the power contribution of each parallel inverter to collectively meet the power demand, one or more of the parallel inverters may be operated at less than the maximum efficiency of the inverter, which tends to increase energy and cost requirements.